A number of household objects become attractive decorative planters once they've become too worn to suit their original use. If you have an old piece of furniture that's obviously beyond restoration, why not turn it into a garden planter instead of sending it to the landfill?
Old chairs are great for this purpose. Get your kids to help brainstorm the design, whether it's painting the chair or adding decorative tile. Once you have the chair design down, cut a hole in the seat that will fit a standard plant pot. Then all you need to do is pick out a decorative pot and a plant or combination of annuals to complete the décor. Because of the weight, it's easier to go ahead and put the pot in the chair before you add the soil and plants or flowers. That way you can also make sure it fits snugly before it's weighted down.